Dispensing apparatus

ABSTRACT

An apparatus for dispensing pre-selected amounts of liquid includes a cylinder having at one end an inlet valve coupled to a reservoir and an outlet valve for delivery of the liquid. A piston is normally retained by a spring adjacent the other end of the cylinder. Delivery is effected by supplying a compressed gas, via a solenoid actuated valve, to the space between the other end of the cylinder and the piston to drive the piston towards the outlet valve end. At the same time, the outlet valve is opened to allow discharge of the liquid. Movement of the piston stops after delivery of the preselected amount, the outlet valve closes, and the spring returns the piston to its normal position, the reverse movement of the piston opening the inlet valve and refilling the cylinder from the reservoir. A manually settable selector switch and a companion servoswitch actuated by movement of the piston cooperate to meter delivery. The manual selector is set to a position corresponding to the amount desired and the compressed air solenoid valve actuated by closing a switch. As the piston moves forward in the cylinder, a wiper on the servoswitch advances until it reaches a contact corresponding to the position set on the manual selector. At that point, the solenoid valve is de-energized, delivery is stopped and the piston is returned to its initial position. Various circuit features are provided to indicate the state of operation of the device, the cumulative amount of liquid dispensed and an empty reservoir.

United States Patent [191 Shinn DISPENSING APPARATUS [75] Inventor:David M. Shinn, Red Bank, NJ.

[73] Assignee: Autobar Systems Corporation, Red

Bank, NJ.

[22] Filed: Aug. 7, 1972 [21] Appl. No.: 278,471

[52] US. Cl 222/14, 222/76, 222/309, 222/389, 222/340 [51] Int. Cl B67d5/30 [58] Field of Search 222/259, 76, 52, 222/14, 17, 22, 333-336, 340,309, 387, 389;

[56] References Cited UNITED STATES PATENTS 3,341,076 9/1967 Wasilewskiet al. 222/334 X 2,420,708 5/1947 Hutshell 222/309 3,122,271 2/1964Grant 222/17 2,824,585 2/1958 Andres 222/504 X Primary ExaminerRobert B.Reeves Assistant E.raminer-H. Grant Skaggs, Jr. Attorney-Granville M.Brumbaugh et a1.

[57] ABSTRACT An apparatus for dispensing pre-selected amounts of 86 38INPUT 54 zxmzusr 84 SOLENOID Jan. 15, 1974 liquid includes a cylinderhaving at one end an inlet valve coupled to a reservoir and an outletvalve for delivery of the liquid. A piston is normally retained by aspring adjacent the other end of the cylinder. Delivery is effected bysupplying a compressed gas, via a solenoid actuated valve, to the spacebetween the other end of the cylinder and the piston to drive the pistontowards the outlet valve end. At the same time, the outlet valve isopened to allow discharge of the liquid. Movement of the piston stopsafter delivery of the preselected amount, the outlet valve closes, andthe spring returns the piston to its normal position, the reversemovement of the piston opening the inlet valve and refilling thecylinder from the reservoir.

A manually settable selector switch and a companion servoswitch actuatedby movement of the piston cooperate to meter delivery. The manualselector is set to a position corresponding to the amount desired andthe compressed air solenoid valve actuated by closing a switch. As thepiston moves forward in the cylinder, a wiper on the servoswitchadvances until it reaches a contact corresponding to the position set onthe manual selector. At that point, the solenoid valve is de-energized,delivery is stopped and the piston is returned to its initial position.Various circuit features are provided to indicate the state of operationof the device, the cumulative amount of liquid dispensed and an emptyreservoir.

9 Claims, 2 Drawing Figures PATENIEUJAN 1 5 mm SHEET 1 BF 2 mm R 3 mm mmww mwhZDOQ PATENTEB JAN 1 5 97% SHEET 2 BF 2 SOLENOID VALVE 1 DISPENSINGAPPARATUS BACKGROUND OF THE INVENTION The present invention relates toapparatus for accurately and automatically dispensing pre-selectedamounts of liquid. The invention is of particular advantage where theamounts of liquid to be delivered are small, e.g., up to 4 ounces, suchas required in the dispensing of alcoholic beverages.

DESCRIPTION OF THE PRIOR ART Various forms of devices for dispensingmeasured amounts of liquid have beendeveloped in the past, em ployingboth mechanical and electrical features. One such apparatus, asexemplified in U.S. Pat. No. l,984,296, includes a pair of axiallydisposed pistoncylinder units with both pistons controlled by a singlepiston rod. One of said cylinders has a pair of oppositely directedone-way valves at its free end, one of said valves arranged to admitliquid from a reservoir and the other to deliver liquid toa user uponforward movement of the piston. The other cylinder is provided withfluid ports on both sides of its two-way piston, whereby selectiveapplication of pressurized fluid to one or the other side of the pistonwill move it in the desired direction, at the same time moving thepiston in the other cylinder to withdraw liquid from the reservoir ordispense it.

To establish the amount of liquid to be dispensed, mechanical orelectrical means are provided in association with an adjustable stoparranged to engage a rear ward extension of the piston rod. The positionof the stop is adjusted manually and manual actuation of the valve meansfor controlling the delivery of pressurized fluid to the second or powercylinder is required.

Although the dual piston cylinder arrangement provides a workablepumping means for'delivering metered amounts of liquid, the dualcylinder construction is cumbersome and the electromechanical controlsystem associated with such apparatus is bulky, unduly complicated andtherefore subject to unreliable and in accurate operation. Moreover, thenecessity for a number of manual steps to initiate the dispensingoperation makes use of such systems relatively slow and subject tofurther error.

Although somewhat more sophisticated electrical selecting and actuatingarrangements for dispensing systerns have been proposed; see, forexample, U.S. Pats. No. 2,080,535 and 3,122,271, no simple controlarrangement for a piston-cylinder metering system which is accurate,reliable in operation and capable of rapid repeated delivery of smallamounts ofliquid has heretofore been developed.

SUMMARY OF THE INVENTION the rest position of the piston, the cylinderis filled with the liquid to be dispensed.

A source of compressed fluid, e.g., air, CO is coupled via a solenoidoperated valve through the cylinder wall and into the space between theone end of the cylinder and the piston when in its rest position.Energization of the solenoid valve supplies pressurized fluid be tweenthe piston and the cylinder end, forcing the piston towards the valvesagainst the biasing force of the spring. The outlet valve is openedsimultaneously with energization of the solenoid and liquid in thecylinder is discharged through the delivery conduit by forward movementof the piston.

At a preselected point in the forward travel of the piston,corresponding to a desired amount of dispensed liquid, the solenoidvalve is de-energized, stopping the supply of pressurized fluid andthereby the piston movement. At the same time, the outlet valve isclosed. The spring now acts to withdraw the piston back to its restposition, exhausting the compressed fluid behind it. During the returnstroke, the inlet valve opens, allowing the suction action of the pistonto refill the cylinder from the liquid reservoir.

The piston stroke, and thus the amount of liquid delivered during asingle operation is determined by electrical circuit means including afirst multiple fixed contact rotary switch having a movable contactmanually settable to any fixed contact position. A second such switch ismounted on the cylinder assembly with its movable contact rotated by apinion gear meshing with a longitudinal rack gear mechanically connectedfor movement with the piston rod. Electrical power is coupled through apush-button operated latching relay to the solenoid valves and to theswitches. When the push-button is pressed, power is supplied to energizethe solenoid valve and deliver pressurized fluid to move the pistonforward. The latching relay maintains the power to the solenoid afterthe push-button is released. As the piston moves, the movable contact onthe associated switch is rotated past the fixed contacts in succession,until it reaches the contact corresponding to that to which the manuallyoperated wiper on the companion switch is set. The circuit to thesolenoid valve is then opened, ending the supply of pressurized gas tothe piston and almost instantaneously stopping its forward movement.

The coil spring, which was put under compression during forward movementof the piston, now returns the piston to its rest position. Uponde-energization, the solenoid valve couples the pressurized fluid behindthe piston to the atmosphere or other low pressure exhaust chamber,thereby removing any impediment to return of the piston. During thisreturn movement, the rotary contact on the cylinder mounted switch isreturned to its starting position.

Indicator lights are provided for signalling the operative condition ofthe dispensing mechanism and the empty state of the reservoir. Countermeans keep a running total of the amount of liquid dispensed. Althoughnot so limited in application, the invention is particularly suited formetered delivery of small preselected amounts, e.g., up to 4 ounces, ofliquid, such as would be required in the dispensing of alcoholicbeverages.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features and advantagesof the invention will become more apparent from the following detaileddescription thereof, taken in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a drawing partially in section and partially broken awayshowing the apparatus of the present invention, including the mechanicaland hydraulic elements and the associated electrical circuitry; and

FIG. 2 is a view taken along line 2-2 of FIG. 1 in a direction of thearrows showing in greater detail the piston-cylinder arrangement and therack and pinion gears forming part of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The liquid dispensing apparatusof the present invention as shown in FIG. 1 comprises a reservoir 11 forthe liquid 12 to be dispensed. In the preferred embodiment illustrated,which is particularly adapted to dispense alcoholic beverages, thereservoir is generally cylindrical, having an open upper end which isadapted to receive the neck 13 of an inverted liquor bottle 14. Flange15, at the bottom of the reservoir, allows it to be mounted in a holeprovided in a convenient planar surface 16. Outlet 17, at the bottom ofthe reservoir, connects with exit duct 18.

A float 19 is provided in reservoir 11. When the bottle 14 has an amplesupply of liquid, the reservoir 11 will fill with liquid 12 until thelevel reaches the open neck 20 of the bottle 14. If the bottle 14contains insufficient liquor to raise the float 19, the level of liquid12 in the reservoir will continue to fall upon operation of theapparatus until float 19 and a magnet 21 contained therein rest in closeproximity to reed switch 22. The magnet then actuates the switch tolight indicator lamp 23 and warn the operator of the low liquid level,at the same time, disabling latching relay 55 to prevent furtheroperation until additional liquid is supplied to reservoir 14, as willbe described in greater detail below.

The delivery mechanism of the dispensing system is shown incross-section in FIG. 2 and comprises a generally cylindrical chamber 24within an outer housing indicated generally by the numeral 60. Thelefthand end of the chamber 32 is closed off byend plate 64 and sealingring 65, both of which are provided with central apertures through whichthe piston rod 28 passes. Suitable O-rings, or other packing means,provide a fluidtight seal.

The righthand end of chamber 24 is closed off by an end wall 66 havingan inlet aperture 68 and an outlet aperture 70. A flap 25, formed of asuitable rubber or plastic material, acts as a one-way valve for theaperture 68. The flap preferably is formed of a single piece of materialcemented or otherwise secured to the end wall 66 adjacent one edge sothat it hingedly deflects away from the plate when subjected to fluidpressure in the direction of the arrow and thereby permits fluid passagethrough the apertures, or is firmly pressed against the end plate whensubjected to fluid pressure in the opposite direction, thereby to sealthe aperture and prevent fluid flow. Communicating with the inlet valveis a suitable fitting adapted to receive inlet conduit 18 (see FIG. 1).

Associated with the outlet opening 70 is a valve, preferably of thesolenoid actuated type as shown. The valve couples the chamber 24 to theoutlet conduit 30. As will be explained hereinafter, the valve 29 isopened at the appropriate time to permit delivery of liquid from thechamber to the receptacle 31 (FIG. 1).

An opening 32 is provided through the housing to receive duct 34 whichserves both to couple pressurized fl'uid to the chamber during thedelivery stroke and as an exhaust line during the return stroke, as willbe described in greater detail hereinafter.

A piston 26 is arranged to be moved longitudinally within chamber 24 andis suitably sealed about its circumference so as to make fluid-tightengagement with the interior wall of the chamber. As will beappreciated, the precise form of the piston is not critical as long asit is of relatively short axial length relative to the respectivechamber. For purposes of effecting the necessary seals with the chamberwalls, O-rings are shown, but any suitable sealing means may be used.

A piston rod 28, secured to the piston by any suitable means, such as ascrew, extends through end members 64 and 65 exteriorly of the housingand is provided with a laterally extending arm 39 fixedly securedthereto near its end. A coil compression spring 32, which may be ofconical shape, is constrained between the arm 39 and the end plate 64.

As indicated above, the liquid to be dispensed is admitted to anddelivered from the chamber 24 through the valves 25, 29 respectively.Movement of piston 26 toward end plate 66 will discharge liquid in thecylinder through the outlet valve 29 which is open at this time, andinto the outlet conduit 30, at the same time tightly sealing inlet valve25. Conversely, retraction of the piston establishes a vacuum, or lowpressure condition, which draws liquid from the reservoir 11, throughinlet conduit 18 and valve 25 into chamber 24. The valve 29 is closedduring the return stroke of the piston.

Forward movement of the piston 26 is effected by supplying pressurizedfluid through conduit 34 to the back side of piston 26. With the valve29 open, the applied pressure will move the piston toward the valve endof the cylinder, discharging liquid through conduit 30. Spring 32 iscompressed during the discharge stroke and, upon relief of pressure onthe piston, will return the piston to its rest position shown in FIG. 2,refilling the chamber from the reservoir.

Delivery of pressurized fluid through conduit 34is controlled by asolenoid operated valve 37 (FIG. 1). A source of pressurized fluid, suchas an air compressor or hydraulic fluid, is coupled-at 54 to the inletport 82 of the valve body. An exhaust port 84 is connected to exhaustline 86 and conduit 34 is coupled to port 88. Operation of the valve iseffected by moving the valve spool 53 between two positionscorresponding to energized and non-energized conditions of the solenoid36. Thus, in the energized condition of the solenoid, the sleeve is sopositioned as to couple pressurized fluid from input 54 to conduit 34.When the solenoid is deenergized (as shown in FIG..1),' the input duct54 is shut and the conduit 34 is connected to exhaust line 86, therebypermitting spring 32 to retract the piston. The valve described is astandard commerically available type and other forms of solenoid valvescapable of performing the required functions may be employed.

Metering of the amount of liquid to be dispensed is accomplished byaccurately predetermining the extent of movement of piston 26 from itsextreme left-hand or rest position, towards the delivery end of thechamber. A servoswitch assembly 42 is mounted exteriorly of the housing60, such as by screws, adjacent the chamber 24. The switch assemblyincludes a fixed plate having a plurality of angularly dispose dcontacts 43, and a rotatable member having a single contact arm 44disposed so as to successively connect with each of the contacts 43 asit is rotated. Contact 45 provides the common or reference contact forthe switch.

,A longitudinally extending rack gear 38 is supported in cantileverfashion by means of arm 39 secured to the piston rod 28 exteriorly ofthe housing 60. The rack 38 is disposed substantially parallel to thepiston rod and will move back and forth therewith. Meshing with the rackgear, is a pinion gear 41 rotatably mounted on the servoswitch assembly.The gear 41 is coupled by means of shaft 45 to the rotatable member ofthe switch assembly so that the latter rotates together with the piniongear. It will be seen then, that movement of the piston rod-pistonassembly effect a corresponding change of position of the movablecontact 44, by means of the intervening rack and pinion assembly.

Associated with the servoswitch assembly 42 is a manual selector switchindicated generally at 46. The latter includes a fixed plate 'having aplurality of contacts 47 which may be equal to or lesser in number thanthe contacts 43, and a rotatable contact 48 whose position may bemanually set by means of knob 49. Contact 50 is the common terminal forthe switch. As shown in FIG. 1, each contact 47 on the manual switch iselectrically connected to a contact 43 on theservoswitch assembly 42. Itwill be understood that each contact 43 corresponds to a particulardisplacement of piston 26; therefore each contact 47 on the manualselector 46 corresponds to the displacement represented by the contact43 to which it is connected. The selector switch may be located remotelyfrom the remainder of the apparatus and preferably is in a positionconvenient to the delivery end of the outlet conduit 30, so that theoperator may set the volume desired as he positions the glass or otherreceptacle 31 to receive the liquid.

As seen in FIG. 1, operation of the dispensing system is controlled byan electrical circuit which provides immediate response and accuratemetering. The circuit elements of FIG. 1 and mechanical elements of FIG.2 are shown in their rest positions, awaiting actuation to deliver apreselected amount of liquid to the receptacle 31.

The operator first adjusts switch 46 to select the amount of liquid tobe delivered. Each of the contacts 47 is electrically connected to acontact 43 on the servoswitch assembly 42 and thus corresponds to apredetermined displacement of the piston 26. Then, with the power on, asindicated by the lighted condition of the bulb 57, the operatormomentarily depresses pushbutton 51. This completes a circuit for thecoil of latching relay 55 from the power source through the reed switch22, the common terminal 45 and movable contact 44 on servoswitch 42.

Energization of the coil of relay 55 moves its armature 56 to theposition indicated by dotted line, where it remains until the coil isagain energized. In its lower (dotted) position, armature 56 connectspower from the source to the solenoid 36. Actuation of the latter movesvalve sleeve 53 to its left-hand position, coupling input line 54 to theconduit 34. Lamp 52 is also energized during actuation of the solenoid36 to advise the operator that the apparatusis in the dispensing portionof its cycle.

Also connected across the powersource upon energization of latchingrelay 55 is solenoid valve 29 at the outlet of the chamber 24. v

With pressurized fluid now coupled into conduit 34, pressure is appliedto the rear face of piston 26 to move it towards the outlet end of thecylinder. Valve 29 is now open and movement of the piston deliversliquid through conduit 30 to the receptacle 31. As will be seen, spring32 is compressed by this movement of the piston.

Advance of the piston 26 and piston rod 28 also moves rack gear 38,causing pinion gear 41 to rotate in a counter-clockwise direction.Movable contact 44 on the servoswitch is then rotated in the samedirection to successively wipe over fixed contacts 43. Upon contact 44leaving its home position, push button 51 is disabled. When movablecontact 44 reaches contact 43a, a circuit is completed from one terminalof the power source, through common terminal 45, movable terminal 44 andfixed contact 43a on the servoswitch assembly 42, over the conductorconnecting contact 43a to contact 47a, and then through rotatablecontact 48 and common terminal 50 on switch 46, through the coil ofrelay 55 and reed switch 22 to the other terminal of the power source.Relay 55 is thereby energized to move its armature 56 to its upper (fullline) position, de-

energizing solenoid 36 and solenoid valve 29, and ex tinguishingindicator lamp 52.

Deenergization of solenoid 36 returns sleeve 53 to the position shown inFIG. 1, allowing the pressurized air behind piston 26 to exhaust throughconduits 34 and 86. Spring 32 returns piston 26 to its rest position asin FIG. 2, and during this return motion, rack 38 rotates pinion 41 in aclockwise direction to return mov able contact 45 to its rest or homeposition, enabling pushbutton switch 51.

Return of the piston 26 to its rest position creates a vacuum or suctionforce in the chamber 24 which draws liquid from the reservoir" 11 intothe chamber through duct 18 and inlet valve 25. Thus, the chamber 24 isrefilled after each delivery. The apparatus is now ready for anotherdelivery cycle upon actuation of push button 51. i

To monitor the amount of liquid dispensed over a number of operatingcycles, a counter may be provided. The counter is energized each timelatching relay 55 is operated to initiate delivery.

Operation of the apparatus is prevented when the reservoir 1 1 is emptyby means of the magnetic element 21 and the reed switch 22. When thereservoir is substantially empty, the float 19 is in a position suchthat the magnet 21 causes reed switch 21 to operate, opening theconnection from the power line to the terminal of the coil of latchingrelay 55 and completing a connection to the indicator lamp 23. Thedisconnection prevents actuation of the delivery mechanism and the lampapprises the operator of the lack of liquid supply.

As indicated hereinabove, the present invention enables reliable,accurate delivery of small amounts of liquid. It has been found that theapparatus is capable of selectively delivering amounts varying by aslittle as one-eighth of a fluid ounce. It will be recognized that theamounts represented by the available positions on manual selector switch46 will depend on the number of available contacts 43 on servoswitchassembly 42 and accordingly, the arrangement is susceptible to a widerange of calibration. The precise and wide range of control availablemakes the apparatus particularly adaptable to delivery of small amountsof liquid, such as would be required in dispensing of alcoholicbeverages.

It will be understood that various modifications of the disclosedstructure will occur to those skilled in the art and it is intended thatthe invention be limited only in accordance with the appended claims.

I claim:

1. Apparatus for dispensing fluids comprising a housing including anelongated chamber having inlet and outlet valves at one end thereof,means for coupling a supply of fluid to be dispensed to said inletvalve, a piston in said chamber adapted to move longitudinally thereintowards and away from said one end, a piston rod connected to'saidpiston and extending longitudinally of said chamber through the housingat the other end thereof, controllable means for supplying pressurizedfluid to said chamber to move said piston towards said valve end, springmeans coupled between said piston rod and said housing for urging saidpiston away from the valve end of the chamber, and manually adjustableelectric circuit means for actuating said controllable means to supplypressurized fluid to said chamber to move said piston towards said valveend a predetermined distance corresponding to the manual adjustment ofsaid electric circuit means, said electric circuit means beingresponsive to said piston moving said predetermined distance to actuatesaid controllable means to stop said supply of pressurized fluid to saidchamber and to exhaust the pressurized fluid already supplied, saidspring meansthereafter being effective to return said piston to a restposition adjacent said other end of the chamber.

2. The apparatus of claim 1 wherein said controllable means comprises asolenoid valve coupling said chamber alternately between a source ofpressurized fluid and exhaust means.

3. Apparatus for dispensing fluids comprising a housing including anelongated chamber having inlet and outlet valves at one end thereof,means for coupling a supply of fluid to be dispensed to said inletvalve, a piston in said chamber adapted to move longitudinally thereintowards and away from said one end, a piston rod connected to saidpiston and extending longitudinally of said chamber through the housingat the other end thereof, controllable means including a solenoid valvecoupling said chamber alternately between a source of pressurized fluidto move said piston towards said valve end and exhaust means, springmeans coupled between said piston rod and said housing for urging saidpiston away from the valve end of the chamber, a source of electricalenergy, latching switch means for actuating said solenoid valve tosupply pressurized fluid to said chamber upon manual actuation, firstmulti-position switch means having a plurality of fixed contacts and amovable contact coupled to said' piston rod for conjoint movement, meansfor selectively enabling a desired one of said fixed contactscorresponding to a predetermined longitudinal displacement of saidpiston, and further circuit means coupling said first multi-positionswitch means to actuate said solenoid valve to connect said chamber tosaid exhaust means, said spring means thereafter being effective toreturn said piston to a rest position adjacent said other end of thechamber.

4. The apparatus of claim 3 wherein said outlet valve is of the solenoidoperated type and is connected to said latching switch means foroperation in conjunction with said solenoid valve whereby said outletvalve is opened to permit fluid flow while pressurized fluid is beingsupplied to said chamber and closed to fluid flow while said chamber isconnected to said exhaust means.

5. The appartus of claim 3 wherein said selective enabling meansincludes a second multi-position switch means having a plurality offixed contacts and a manually positionable movable contact, and meansconnecting the fixed contacts of said second switch means to selectedfixed contacts of said first switch means, whereby manual positioning ofthe movable contact of said second multi-position switch means iseffective to predetermine the extent of longitudinal displacement of thepiston.

6. The apparatus of claim 5 wherein said first multiposition switch isof the rotary type and is mounted on said housing with said movablecontact secured to a rotatable shaft, and said means coupling saidmovable contact to said piston rod comprises pinion gear means securedto said shaft and rotatable therewith, and rack gear means secured tosaid piston rod for longitudinal movement therewith adapted to mesh withsaid pinion gear means.

7. The apparatus of claim 6 further comprising counter means coupled tosaid latching switch means for recording the movement of said piston.

8. Apparatus for selectively dispensing predetermined amounts ofalcoholic beverages and the like comprising, reservoir means for storinga quantity of the liquid to be dispensed, pump means including acylinder and piston, said cylinder having at one end thereof an inletvalve coupled to said reservoir and an outlet valve coupled to adelivery conduit, said piston adapted to move longitudinally 'in saidcylinder and having a front surface facing the valve end of the cylinderand a rear surface facing the other end of the cylinder, a piston rodextending from said rear face and through the wall of said cylinder,coil spring means coupling said cylinder and said piston rod to maintainsaid piston normally adjacent to but slightly spaced from said other endof said cylinder, conduit means coupled through said cylinder wall andinto the space between the rear surface of said piston and the other endof said cylinder, solenoid valve means coupling said conduit meansselectively to a source of pressurized fluid and exhaust means, saidconduit normally being coupled to said exhaust means, a source ofelectric power, latching switch means coupling said power source to saidsolenoid valve, first multi-position switch means mounted exteriorly ofsaid cylinder and having a plurality of fixed contacts and a movablecontact, means coupling said movable contact to said piston rod forconjoint movement, second multi-position switch means having a pluralityof fixed contacts and a manually positionable movable contact, meansconnecting the fixed contacts of said second switch means to selectedfixed contacts of said first switch means, pushbutton means foractuating said latching switch means to operate said solenoid valve tocouple pressurized fluid to said conduit, thereby to move said pistontowards the valve end of said cylinder and discharge liquid in saidcylinder through said outlet valve and delivery conduit, said movablecontact on said first switch means being moved conjointly withsaid'piston rod, and

further circuit means operable upon said movable contact of said firstswitch reaching the fixed contact connected to the fixed contact of thesecond switch on which the movable contact of the latter has beenmanually positioned to actuate said latching switch means to operatesaid solenoid valve means to change the connection of said conduit fromsaid source of pressurized fluid to said exhaust means, whereby forwardmotion of the piston ceases and the spring means is effective to tionand for disabling said dispensing apparatus.

1. Apparatus for dispensing fluids comprising a housing including anelongated chamber having inlet and outlet valves at one end thereof,means for coupling a supply of fluid to be dispensed to said inletvalve, a piston in said chamber adapted to move longitudinally thereintowards and away from said one end, a piston rod connected to saidpiston and extending longitudinally of said chamber through the housingat the other end thereof, controllable means for supplying pressurizedfluid to said chamber to move said piston towards said valve end, springmeans coupled between said piston rod and said housing for urging saidpiston away from the valve end of the chamber, and manually adjustableelectric circuit means for actuating said controllable means to supplypressurized fluid to said chamber to move said piston towards said valveend a predetermined distance corresponding to the manual adjustment ofsaid electric circuit means, said electric circuit means beingresponsive to said piston moving said predetermined distance to actuatesaid contRollable means to stop said supply of pressurized fluid to saidchamber and to exhaust the pressurized fluid already supplied, saidspring means thereafter being effective to return said piston to a restposition adjacent said other end of the chamber.
 2. The apparatus ofclaim 1 wherein said controllable means comprises a solenoid valvecoupling said chamber alternately between a source of pressurized fluidand exhaust means.
 3. Apparatus for dispensing fluids comprising ahousing including an elongated chamber having inlet and outlet valves atone end thereof, means for coupling a supply of fluid to be dispensed tosaid inlet valve, a piston in said chamber adapted to movelongitudinally therein towards and away from said one end, a piston rodconnected to said piston and extending longitudinally of said chamberthrough the housing at the other end thereof, controllable meansincluding a solenoid valve coupling said chamber alternately between asource of pressurized fluid to move said piston towards said valve endand exhaust means, spring means coupled between said piston rod and saidhousing for urging said piston away from the valve end of the chamber, asource of electrical energy, latching switch means for actuating saidsolenoid valve to supply pressurized fluid to said chamber upon manualactuation, first multi-position switch means having a plurality of fixedcontacts and a movable contact coupled to said piston rod for conjointmovement, means for selectively enabling a desired one of said fixedcontacts corresponding to a predetermined longitudinal displacement ofsaid piston, and further circuit means coupling said firstmulti-position switch means to actuate said solenoid valve to connectsaid chamber to said exhaust means, said spring means thereafter beingeffective to return said piston to a rest position adjacent said otherend of the chamber.
 4. The apparatus of claim 3 wherein said outletvalve is of the solenoid operated type and is connected to said latchingswitch means for operation in conjunction with said solenoid valvewhereby said outlet valve is opened to permit fluid flow whilepressurized fluid is being supplied to said chamber and closed to fluidflow while said chamber is connected to said exhaust means.
 5. Theappartus of claim 3 wherein said selective enabling means includes asecond multi-position switch means having a plurality of fixed contactsand a manually positionable movable contact, and means connecting thefixed contacts of said second switch means to selected fixed contacts ofsaid first switch means, whereby manual positioning of the movablecontact of said second multi-position switch means is effective topredetermine the extent of longitudinal displacement of the piston. 6.The apparatus of claim 5 wherein said first multi-position switch is ofthe rotary type and is mounted on said housing with said movable contactsecured to a rotatable shaft, and said means coupling said movablecontact to said piston rod comprises pinion gear means secured to saidshaft and rotatable therewith, and rack gear means secured to saidpiston rod for longitudinal movement therewith adapted to mesh with saidpinion gear means.
 7. The apparatus of claim 6 further comprisingcounter means coupled to said latching switch means for recording themovement of said piston.
 8. Apparatus for selectively dispensingpredetermined amounts of alcoholic beverages and the like comprising,reservoir means for storing a quantity of the liquid to be dispensed,pump means including a cylinder and piston, said cylinder having at oneend thereof an inlet valve coupled to said reservoir and an outlet valvecoupled to a delivery conduit, said piston adapted to movelongitudinally in said cylinder and having a front surface facing thevalve end of the cylinder and a rear surface facing the other end of thecylinder, a piston rod extending from said rear face and through thewall of said cylinder, coil spring means coupling said cylinDer and saidpiston rod to maintain said piston normally adjacent to but slightlyspaced from said other end of said cylinder, conduit means coupledthrough said cylinder wall and into the space between the rear surfaceof said piston and the other end of said cylinder, solenoid valve meanscoupling said conduit means selectively to a source of pressurized fluidand exhaust means, said conduit normally being coupled to said exhaustmeans, a source of electric power, latching switch means coupling saidpower source to said solenoid valve, first multi-position switch meansmounted exteriorly of said cylinder and having a plurality of fixedcontacts and a movable contact, means coupling said movable contact tosaid piston rod for conjoint movement, second multi-position switchmeans having a plurality of fixed contacts and a manually positionablemovable contact, means connecting the fixed contacts of said secondswitch means to selected fixed contacts of said first switch means,push-button means for actuating said latching switch means to operatesaid solenoid valve to couple pressurized fluid to said conduit, therebyto move said piston towards the valve end of said cylinder and dischargeliquid in said cylinder through said outlet valve and delivery conduit,said movable contact on said first switch means being moved conjointlywith said piston rod, and further circuit means operable upon saidmovable contact of said first switch reaching the fixed contactconnected to the fixed contact of the second switch on which the movablecontact of the latter has been manually positioned to actuate saidlatching switch means to operate said solenoid valve means to change theconnection of said conduit from said source of pressurized fluid to saidexhaust means, whereby forward motion of the piston ceases and thespring means is effective to return the piston to its normal position,the return movement of said piston creating a suction force operable todraw liquid from said reservoir through said inlet valve to fill saidcylinder.
 9. The apparatus of claim 8 further comprising means coupledto said reservoir for indicating an empty condition and for disablingsaid dispensing apparatus.